The utilization of blood taken from donors and infused into recipients is well known for purposes of treating medical emergencies and other conditions. More recently, selected blood components have been harvested from blood for subsequent infusion into recipients requiring blood component therapy. As used herein, "harvesting" means the separation/removal of a particular type of blood component from remaining portions of the whole blood.
In order to harvest blood components, blood is removed from a donor by a needle assembly or other blood access device and is thereafter processed utilizing centrifugation or other appropriate separation techniques to isolate and collect the desired components. This procedure is carried out most effectively in an on-line, continuous process wherein blood is removed from a donor, processed through a disposable extracorporeal circuit to obtain the desired components, and returned to the donor. Once the harvested blood components are collected in this manner, it is often necessary to subject such components to an "off-line yield determination technique." As used herein, "off-line yield determination technique" means any laboratory analysis performed in accordance with a predetermined laboratory testing regime (i.e., utilizing a particular blood component counting technique with a specific predetermined apparatus and protocol). For instance, in the case of harvested platelets laboratory testing is required (e.g., governmental/industry regulations/standards) or otherwise desired to identify platelet yield prior to distribution. More particularly, under some circumstances associating a platelet yield (e.g., the number of platelets in a harvested collection or any other value from which such may be derived) within a particular collection of platelets may be integral in the provision of such as a platelet product.
Laboratory testing of blood components typically entails the use of expensive equipment and relatively time-consuming procedures, and therefore the use of off-line yield determination techniques is not feasible for many blood harvesting facilities. Consequently, these facilities are forced to ship their collections of harvested blood components to off-site, third-party laboratories meeting the relevant requirements. As can be appreciated, such third-party laboratory testing of harvested blood components adds significant cost and delay in the provision of blood component products.
In the latter regard, certain "on-line yield determination techniques" have been developed to assist blood component harvesting facilities in donor yield/schedule planning and donor-specific harvesting procedures. As used herein, "on-line yield determination technique" means any technique, other than off-line yield determination techniques (i.e., actual laboratory testing), to forecast the yield of harvested/collected blood components. Of particular interest, a platelet yield prediction technique has been developed which is based upon donor-specific physical data (e.g., donor blood volume, hematocrit, and platelet precount) and harvest procedure-specific information (e.g., needle information, device collection efficiency, volume of concurrent source plasma collection, whole blood and anticoagulant flow rates, anticoagulant infusion rate, and procedure duration). Relatedly, harvesting/collection monitoring techniques have been employed in which, for example, optical measurements are taken during platelet collection to determine platelet concentration from which platelet yield is determined. By way of example, each of the noted prediction and monitoring techniques are incorporated in the COBE Spectra.TM., a product of Cobe BCT, Incorporated, 1201 Oak Street, Lakewood, Co. 80215.
While such prediction and monitoring techniques have proven to be useful for planning purposes, experience reflects discrepancies between yield values generated thereby and the corresponding yield values obtained by off-line yield determination techniques. Moreover, it is generally believed that there is a laboratory-to-laboratory variance in determining yields, even when employing similar off-line yield determination techniques.